Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 degrees C and increases with RTA temperature. The following CFA at 300-500 degrees C leads to further B deactivation, while that at 600-800 degrees C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B2I complexes results in further B deactivation in the following CFA at 300-500 degrees C. On the contrary, the dissociation of BI pairs during the following CFA at 600-800 degrees C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition. (C) 2014 AIP Publishing LLC.